Barracuda Blocklist (BRBL) Removal and Barracuda Gateway Blocks

There are two different "Barracuda blocks," and they need different fixes. If your IP is on the Barracuda Reputation Block List (BRBL), look it up at barracudacentral.org/lookups, fix the cause, and submit one removal request with a real explanation; Barracuda says valid requests are typically handled within 12 hours. If your IP isn't listed and one company's Barracuda gateway is still rejecting you, it's that company's filter settings, and only their admin can change them.

For the general blocklist playbook, see We Got Blocklisted. This page is the Barracuda-specific part.

Which Barracuda block do you have?

Barracuda sells email security gateways (today, Email Gateway Defense in the cloud, plus older on-premises appliances) to businesses, schools and governments. Those gateways check incoming mail against Barracuda's own reputation data, and that same data is published as a free DNS blocklist, the BRBL, that other mail servers can query at b.barracudacentral.org.

So a Barracuda-flavored bounce can come from three places:

A BRBL rejection from a mail server that uses the list looks like this (this one is Postfix):

554 5.7.1 Service unavailable; Client host [203.0.113.7] blocked
using b.barracudacentral.org

Some bounces also include an old barracudanetworks.com/reputation link that may no longer load. Use the lookup at barracudacentral.org instead.

If you're on the BRBL

Why Barracuda lists IPs

Barracuda Central lists IPs with a "poor" reputation and says it manually verifies every IP marked poor. Its own list of likely reasons:

• The mail server has a virus and has been sending spam
• The mail server may be misconfigured
• A PC on your network is infected with a virus or botnet software
• You're on a dynamic IP that a known spammer used before you
• Your marketing team is sending bulk mail that doesn't comply with CAN-SPAM
• An insecure wireless network is letting outsiders send through your connection
• Rarely, the recipient's own Barracuda is misconfigured

Notice how many of those are about infrastructure rather than marketing. If you send from an office network or your own mail server, one infected laptop sending through the shared office IP is enough.

How to get delisted

1. Confirm the listing. Look up the IP at barracudacentral.org/lookups. Note whether it shows as poor.
2. Find the cause before you ask. If you run your own network, look for infected machines and anything else sending on port 25. Make sure only your real mail server can send outbound on port 25, and that it has reverse DNS (a PTR record such as mail.example.com for 203.0.113.7) that resolves back to the same IP. If you send through an ESP, check your recent campaigns for new list sources or a spike in complaints.
3. Fix it, and confirm the bad traffic has stopped.
4. Submit one removal request at barracudacentral.org/rbl/removal-request. It asks for the IP, your email address, a phone number, and a reason. Write a short, specific reason: what caused it and what you changed. "An infected workstation at 203.0.113.7 was sending spam; it's been cleaned and outbound port 25 is now blocked for everything except our mail server" is the right shape.
5. Don't resubmit. Barracuda says requests with invalid information, and multiple requests, are ignored. Requests with a valid explanation are typically handled within 12 hours.

Removal is free. If you're on an ESP's shared IPs, the ESP should submit the request, since they control the IP.

If you're not listed but a Barracuda gateway still blocks you

This is the more confusing case, and it's common. Your IP looks fine at barracudacentral.org, but mail to one particular company keeps bouncing or disappearing, and their mail runs through Barracuda.

That gateway runs a stack of checks beyond reputation, and the recipient's admin controls most of them. According to Barracuda's documentation for Email Gateway Defense, these include:

• Rate control. Limits how many recipients a single sending IP can reach at that domain in a 30-minute window. Exceeding it gets you deferred, not blocked. A big internal announcement or a bulk send to many people at one company can trip it.
• Suspicious email monitoring. Defers mail with common subject lines and suspicious content. It's usually accepted on a later retry.
• IP analysis. Barracuda reputation, any external blocklists the admin turned on, and the admin's own allow and block lists. The admin can block your IP or domain directly.
• Sender authentication. SPF and related checks. A missing or broken SPF record or DKIM signature can fail here. Run your domain through the email checker.
• Spam scoring and intent analysis. Content scoring and checks on links, phone numbers and embedded content. A link to a domain with a bad reputation can sink an otherwise clean message.
• Email categorization. Admins can act on categories of legitimate bulk mail. The "Marketing Materials and Newsletters" category is one of them, so a perfectly legitimate newsletter can be quarantined or blocked because the recipient's admin chose to block that category.

Messages blocked by reputation or external blocklists don't appear in the recipient's Message Log, which means the recipient may honestly not see your mail anywhere.

What to do:

1. Read the bounce or deferral text closely and note whether it's a temporary (4xx) or permanent (5xx) failure.
2. Check your authentication with the email checker, and pull the headers of a message that did get through with the header analyzer.
3. Ask your contact at the recipient company to have their IT team check the gateway's logs for your message. They can see why it was blocked and, if appropriate, add your IP or domain as an exemption.

There's no form at Barracuda that overrides a customer's own policy. The fix runs through the recipient.

How to confirm it's fixed

• The lookup at barracudacentral.org no longer shows the IP as poor.
• Bounces citing b.barracudacentral.org stop across the domains that were rejecting you. Allow time for DNS caching.
• For a gateway policy block, send a test to your contact at the recipient and have them confirm it arrived and wasn't quarantined.

Keeping it from coming back

• Lock down port 25. Only your mail server should be able to send outbound on port 25. This one control stops most infected-PC listings.
• Keep reverse DNS correct on any IP that sends mail, and update it when servers move.
• Patch and scan. Infected machines and compromised web applications are the most common infrastructure causes.
• Mail people who asked. For marketing mail, the usual rules apply. See why emails go to spam and which blocklists actually matter.

When to get help

If you've been delisted and relisted more than once, or a key customer's Barracuda gateway keeps blocking you and their IT team can't explain why, it's worth having someone look at your infrastructure and sending patterns together. Get in touch.

FAQ

How long does Barracuda take to remove an IP?

Barracuda says removal requests that include a valid explanation are typically handled within 12 hours. Requests with invalid information, and repeat requests, are ignored.

Does Barracuda charge for delisting?

No. The removal request at barracudacentral.org is free.

I'm not on the Barracuda list, so why does a Barracuda customer keep blocking me?

Their gateway has its own policies: rate limits, authentication checks, content scoring, category rules for marketing mail, and the admin's own block lists. Ask the recipient's IT team to check their gateway logs.

Does the BRBL affect Gmail or Outlook?

Barracuda's reputation data is used in Barracuda's own products and by mail servers that choose to query the BRBL. Neither Google nor Microsoft documents using it, and their filtering runs on their own systems.